Related:

• Not to be a socialist at twenty is proof of want of hea
  o be one at thirty is proof of want of head. -- Georges Clemenceau (1841-1929)...
• If you are not an idealist by the time you are twenty you have no heart, but if you are still an idealist by the time you are thirty, you don't have a head.
  -- Randolph Bourne...
• An example is not proof.
• Lack of proof <> proof of lack.
• You think it is a want of judgment that he changes his opinion.
  Do you think it a proof that your scales are bad because they vibrate with every additional weight that is added to either side?...
• I said "fool-proof, NOT stupid-proof
• QOTD: "This is a one line proof... if we start sufficiently far to the left.
• The proof is left to the student as a pudding.
• The exercise is proof of the student.